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Consensus sequences are regularly occurring sets of proteins or nucleotides in DNA that can be used to predict locations and binding sites. Scientists use statistical formulas and sequence motifs to analyze genetic information and relate it to biological functions and evolutionary patterns.
A consensus sequence is a set of proteins, or nucleotides in deoxyribonucleic acid (DNA), that appear regularly. DNA is made up of nucleotides and each nucleotide is made up of a phosphate, a sugar and a nitrogenous base. The nitrogenous bases can be adenine (A), thymine (T), guanine (G) and cytosine (C). The sequence of these chemical bases determines the genetic code of an organism. The genetic code is like an instruction upon which an organism is built and maintained. Molecular biologists often use statistics to predict the location of sequences or to figure out where particular molecules tend to bind. Formulas can be used to represent the positions where amino acid sequences stay the same and the positions where they vary. In the case of a consensus promoter sequence, for example, a particular type of enzyme can bind to sites on similarly sequenced proteins.
Geneticists, like researchers in many scientific disciplines, often use substitutions to simplify complex systems. There are so many amino acid bases and genes in the body that scientists can’t count them unless there is a general system for doing so. A consensus sequence can appear in many locations in DNA and in various living things. The similarities and differences that tend to occur can be indicated by a formula.
Statistically, scientists can sort genetic sequences to look for patterns. Repeating patterns, called sequence motifs, are generally used to represent genetic areas that control specific biological processes. Consensus sequences can also offer insight into how proteins are synthesized or how molecules are guided within a cell.
In consensus sequence notation, the position of some nucleotides can show that they are always in the position represented. It may also be indicated that one nucleotide or another may be present. In this case, the frequency with which one amino acid appears instead of another is generally not indicated. Sometimes a graphical model is used to indicate this frequency, by increasing or decreasing the size of the symbols. Some software programs can automatically generate sequence logos.
Often, a consensus sequence corresponds to a recognized protein binding site. To accurately represent sequences on the genome, mathematical formulas are often used. These include statistical formulas such as logarithms and numerical values, which can be positive or negative, to represent the location of the genetic information. Processes in the genome for normal biological functions, as well as those related to disease, can be analyzed in this way.
Mathematical representations of a consensus sequence generally provide a DNA model and amino acid models. An exact picture is not usually provided. The sequences, however, can help scientists relate functional aspects of different parts of the genome to the evolutionary patterns of organisms.
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